They provided instant warm, hot or boiling hot water whenever I wanted, at the touch of a button. This meant I could make any kind of tea, or soup, or hot chocolate, or instant noodles, without having to wait for water to boil.

I found these hot water boilers incredibly useful – well designed, easy to use, and I loved the little melody they played when the water was at the right temperature.

So when I got back from holiday, I researched everything I could about Japanese hot water dispensers. I wanted one for my very own!

And I was relieved to find that in the US, the Japanese machines have buttons labeled in English and an easy to read English language instruction manual. I knew I had to own one, but it took me a while to figure out the best model for my needs.

My favorite: the Zojirushi CV-DSC40 VE hot water boiler

I took a long time figuring out all its features, so in this review I want to share why this is my favorite Zojirushi. I think any tea lover will want to own this amazing machine, and I’ll do my best to give you all the info you need.

In my research, I quickly decided that there was no need to look at other brands than Zojirushi.

I know there are knockoffs and rival brands out there, but Zojirushi was literally everywhere in Japan and was the clear front runner.

I already knew the Zojirushi brand from their fuzzy logic rice cookers, which are also the top of the line for the US as well as in Japan.

Plus, I just love how easy their machines are to operate. Basically, I didn’t want a knockoff; I wanted a well-made appliance that would last me for years and years.

While I was looking around online, I found out that there are many different models of Zojirushi hot water heaters.

They differ in size — some are so small that they aren’t that different from a western electric kettle, some are so big that you could use them to make soup for an orphanage. And there are different styles and features to choose from, too. This can make it hard to choose, but I hope this review will help with that.

Save energy with the thermos feature

Double walled stainless steel vacuum insulation

So, I talked about how the thermos feature was the deciding factor for me in choosing this model. What is that, exactly?

Basically, the Zojirushi CV-DSC40 is so well insulated that it acts like a giant thermos or hot water bottle. That is why Zojirushi calls it a hybrid — it’s a thermos as well as an electric hot water kettle.

Double-walled vacuum insulation means that between the hot water and the outside of the tea dispenser are two walls of stainless steel. The space between these walls is vacuum-sealed.

Just like a Mr Bento will keep food or drink warm for hours, the Zojirushi CV-DSC40 will keep the water warm for hours without using any electricity.

It will only use electricity for those few moments when the water needs to be brought back up to the preset temperature. And you can set a timer so you will have hot or boiling water exactly when you need it.

Most other Zojirushi hot water heaters don’t have this extra double-walled insulation. I think this is an essential feature — the standard model hot water heater is already energy efficient, but the extra insulation turns the Zojirushi CV-DSC40 into a real energy-saver.

Water capacity

This model’s water capacity is 4 liters. That’s a little over 1 gallon.

This may seem like a lot of hot water, but you go through it quickly, especially when you also use the hot water for cooking.

4 liters is perfect for me, and I think it would be perfect for any family from 2 up to 4 people.

It doesn’t take very long to heat up this amount of water, and you only have to refill the machine every two days. The water stays fresh and at the perfect temperature. And it’s easy to refill: open up the top of the machine and pour in water from a jug or even straight from the tap.

There is also a smaller 3 liter model hot water heater, the Zojirushi CD-WBC30, which would be perfect for single households. However, this model does not have the double-walled stainless steel insulation.

Temperature settings

Multiple temperature settings = perfect tea!

The Zojirushi CV-DSC40 has three temperature settings: 175°F, 195°F, and 208°F. It also reboils at 212°F.

In other words, the water can be warm, hot, or boiling hot. If you drink a lot of tea, these settings are incredibly useful.

As you may know, green tea and oolong tea taste best when made with water that’s warm, but not boiling hot.

Boiling water often makes the tea bitter. For expensive high quality green tea, the water temperature should be even lower.

If you boil water on the stove or with an electric kettle, that means waiting for the water to cool down before you can make tea.

And then how do you know what the water temperature actually is? Usually you end up guessing, and the result is bitter tea or lukewarm tea. With the Zojirushi, you can make the perfect pot or cup of tea every time.

Which temperature setting should you use?

212°F and 208°F: Use this setting for black tea, rooibos tea, instant noodles, instant coffee, pour-over coffee, instant hot chocolate, instant soup or oatmeal. You can also use this setting for cooking: prefill a pan with hot water for cooking pasta, rice, soup or vegetables. The water is boiling or very near boiling hot, so please be careful!

195°F: Use this setting for oolong tea. Oolong tea is fermented green tea, and it falls between green and black tea where water temperature is concerned.

Some other models of Zojirushi hot water boilers also have a 140°Fsetting: the Zojirushi CV-DSC40 does not.

I personally haven’t found this to be a problem, because 140°F is not very hot, and hence not very useful for cooking or making tea or coffee.

The only use I have found for this low temperature setting is for brewing very high grade, expensive Japanese green tea such as Gyokuro. This tea has such a delicate flavour that it will taste best brewed at 140°F.

However, if you drink such high quality green tea, you can still use the 175°F temperature setting. You can pour the hot water into a cold teapot or mug, and let it cool down for a minute before adding your high grade green tea, and it will be at the right temperature.

One thing is certain: your tea won’t taste bitter if you use the right Zojirushi setting to brew it, and if you let it steep for no more than 5 minutes before drinking.

The steam vent is a small slot at the back of the Zojirushi's lid.

Steam Vent Safety

When you’re boiling 4 liters of water, there’s going to be steam.

For safety’s sake, that steam had better go somewhere! That’s why there is a steam vent on top of the Zojirushi hot water machine.

This does mean that you will need to be careful about where you position your hot water dispenser. If you place it directly beneath a kitchen cabinet, the steam could cause the underside of the cabinet to warp.

However, the Zojirushi makers have cleverly placed the machine on a lazy-susan device, which means you can easily spin the whole unit round until the steam can safely escape.

Looks and Finish

Looks aren’t everything, but I do think they matter, especially for an appliance that you’re going to be using multiple times every day.

I find this much more sleek and professional looking than the white and light-coloured plastic exteriors that some other models have. Stainless steel is also very easy to wipe off, and almost impossible to stain.

Using the Timer Setting

The timer is a very handy feature. It’s easy to set, and it is another energy saver: by setting the timer, you turn off the heater until the time you need hot water.

You can set the timer for anywhere between 6 and 10 hours in advance.

If you set it at night for 8 hours, for example, the heater will turn itself off at night. In the morning it will turn itself on, and provide you with hot water just when you need it for your breakfast tea, coffee, or even oatmeal.

Maintenance and Cleaning

If you live in an area with hard water, and you use tap water for your Zojirushi, you will eventually find calcium buildup in your machine. This is easy to remove.

The interior of the hot water boiler has a non-stick coating over the stainless steel, so the acid will not harm your machine. Every 3 months or so, you can use this product to descale your machine. If you run out of citric acid, you could also use concentrated lemon juice.

You may prefer to use filtered water instead to prevent calcium buildup.

If you only use filtered water with your machine, for example by pouring it from a filtered Brita pitcher, you may never need to descale it at all, or perhaps only once every few years.

To clean the outside of the machine, simply wipe with a clean cloth. The stainless steel finish ensures that dirt comes off easily.

Safety Features

You press two buttons before hot water comes out. This prevents accidents and spillage.

The Zojirushi has a number of safety features to prevent accidents like spilling hot water.

You can tell that their design team have thought a lot about possible accidents and ways to prevent them.

The safety features are well designed, and I find them all very useful:

A sensor shuts off the boiler if the tank is empty. That means it can never boil dry.

The boiler also stops working if the lid is left open. This provides additional security: no clouds of steam in your kitchen because you forgot to close the lid.

When the machine is running low on water and needs to be refilled, it will play a beep or a melody. In other words, you won’t suddenly run out of hot water.

The power cord is magnetic. If someone tugs or yanks at it, it will disconnect. This means the machine won’t fall or tip over.

The body of the hot water heater is insulated, so the outside is cool to the touch.

Getting hot water requires you to press two buttons: first the Unlock button and then the Dispense button. Only then will hot water come out. That means it is impossible to press a wrong button and spill hot water. This safety lock feature is especially great when you have children.

User Reviews and Ratings for the Zojirushi CV-DSC40

The reviews are very positive. Here are a few quotes I pulled more or less at random:

“If you drink tea or would use boiling water on a daily basis, this is a staple for your kitchen.”

“I especially recommend it if you’re a Macha tea fan, as it makes the process remarkably fast and easy!”

“I was a bit concerned at first because of the price. However, I use this daily for breakfast cereal, hot tea, and at least a gallon of iced tea. It is in use for at least 16 hours – often being refilled multiple times. In summary, it has been a complete joy.”

“I’ve had this boiler for almost 2 years now and it still works and looks like new.”

“We use this with a Chemex all-glass coffee maker. Set it before we go to sleep each night and it heats up to perfect brewing temperature before we wake up. 8 O’Clock Coffee ($4 a pound from BJs) done this way tastes better than the hundreds of dollars worth of Starbucks and Peets that we used to brew with the old drip coffee maker.”

Study Shows: Hibiscus Tea Lowers Blood Pressure

Just 3 cups of hibiscus tea a day could reduce blood pressure, a study has shown.

Sixty-five people aged between 30 and 70 with "at risk" blood pressure levels were split into two groups. The first group drank hibiscus tea three times a day. The second group drank hibiscus-flavored water.

After six weeks, the hibiscus group showed an average fall of 7.2 % in blood pressure. Some even recorded a 13.2 % drop. The placebo group recorded a 1.3 % drop.

All-natural hibiscus tea contains antioxidants, which have been linked to many health benefits, including protection against heart disease and cancer.

Nutrition scientist Diane McKay, PhD, of Tufts University in Boston, presented the study to the American Heart Association's annual conference.